In the production of such insulating window panes of a rectangular outline, at least two registering glass plates are stacked with interposition of a spacer frame running around the edges of these plates. To form an integral unit, with the space between the plates hermetically sealed against the atmosphere, it is conventional practice to apply an adhesive to the edges of the stack so as to bond the plates and the spacer frame rigidly to one another. After edgewise injection of the adhesive between the glass plates and the spacer frame, the stack is compressed with or without heating so as to activate the adhesive and distribute it uniformly over the surfaces to be bonded. Since the dimensions of the plates may vary considerably, it has been found advantageous to clamp the stack in two steps between a first and a second pair of L-shaped press jaws with legs long enough to accommodate the largest plates contemplated. In these clamping steps the jaws are complementarily oriented, each pair of jaws clamping two adjoining stack edges while the adhesive is being applied thereto.
If the two presses are inserted in a straight-line transport path, two separate control stations are required to monitor these edge-sealing operations and to handle the respective adhesive injectors which are trained upon the stacks about to be clamped in the two presses. Heavy-duty synthetic-resin adhesives generally used in such processes, e.g. two-component epoxy resins, are sensitive to excessive delays or improper handling so that skilled personnel must man the two stations.
Such a duplication of control stations and of adhesive-injection devices adds considerably to the production cost of insulating window panes or similar units produced in this manner. Moreover, the operator or operators at each station are idle much of the time, as during the curing of the injected adhesive in the closed press.